In history class, the girl to boy ratio is $4$ to $8$. If there are a total of $48$ students, how many boys are there?
Solution: A ratio of $4$ girls to $8$ boys means that a set of $12$ students will have $4$ girls and $8$ boys. A class of $48$ students has $4$ sets of $12$ students. Because we know that there are $8$ boys in each set of $12$ students, the class must have $4$ groups of $8$ boys each. There is a total of $32$ boys in history class.